#include <iostream>
using namespace std;
const int N = 100010;
int n;
char s[N];
char ret[N];
int main()
{
	cin >> n >> s;
	int hash[26] = { 0 }; 

		int maxIndex, maxCount = 0;
	for (int i = 0; i < n; i++)
	{
        if (maxCount < ++hash[s[i] - 'a'])
        {
            maxCount = hash[s[i] - 'a'];
            maxIndex = s[i] - 'a';
        }
    }

    if (maxCount > (n + 1) / 2) cout << "no" << endl;
    else
    {
        cout << "yes" << endl;
        int index = 0;
     

            while (maxCount--)
            {
                ret[index] = maxIndex + 'a';
                index += 2;
            }
    
            for (int i = 0; i < 26; i++)
            {
                if (hash[i] && i != maxIndex)
                {
                    while (hash[i]--)
                    {
                        if (index >= n) index = 1;
                        ret[index] = i + 'a';
                        index += 2;
                    }
                }
            }
    

            for (int i = 0; i < n; i++) cout << ret[i];
        cout << endl;
    }

    return 0;
}